Place the chicken thighs in a large pot along with the chopped onion and minced garlic.
Pour in the chicken broth and add the apple cider vinegar, chili powder, cumin, oregano, smoked paprika, salt, black pepper, and cayenne pepper if desired.
Bring the mixture to a vigorous boil over medium-high heat.
Once boiling, lower the heat to a gentle simmer, cover the pot, and let it cook for about 30 to 40 minutes until the chicken is tender and cooked through.
Remove the chicken from the pot and shred it using two forks.
Return the shredded chicken to the pot, mixing it well with the flavorful broth.
In a separate skillet, warm each corn tortilla over medium heat for about 30 seconds on each side until they are soft and pliable.
Assemble the tacos by placing a generous scoop of the chicken mixture onto each tortilla.
Top the tacos with fresh cilantro and diced onion.
Serve with lime wedges on the side for squeezing over the tacos before enjoying.